The present invention relates to a solid-state image sensing device for receiving the optical image of an object formed on a light-receiving surface on which photoelectric converters are arranged in a matrix.
A solid-state image sensing device integrally comprises a group of pixels arranged in a matrix with a photoelectric conversion function and accumulation function, and a circuit having a scanning function of sequentially extracting, in time-series, signal charges accumulated in the respective pixels. As such a solid-state image sensing device, there is a MOS image sensing device (CMOS image sensor) having a CMOS (Complementary Metal Oxide Semiconductor) structure in which power consumption is low and peripheral circuits can be monolithically integrated.
As shown in FIG. 4, this CMOS image sensor comprises a plurality of photoelectric converters 301 arranged in a matrix to perform photoelectric conversion and charge accumulation. Each photoelectric converter 301 is adjacent to a circuit region 302 for extracting signal charges. The photoelectric converter 301 and circuit region 302 constitute a photoelectric conversion cell 305.
A power supply line for supplying a power supply voltage or the like to the photoelectric converter 301 and circuit region 302 is laid in a Y-direction wiring region 303 between respective photoelectric conversion cells 305 adjacent in the X direction. A reset signal line for sending a reset signal to the photoelectric converter 301 and circuit region 302, a selection signal line, and the like are laid in an X-direction wiring region 304 between respective photoelectric conversion cells 305 adjacent in the Y direction. The circuit region 302 is connected to the power supply line via a contact 303a.
A light-shielding member 310 covers the respective photoelectric conversion cells 305 arranged in a matrix. Openings 311 are formed in the light-shielding member 310 at positions corresponding to the centers of the respective photoelectric converters 301.
The detailed circuit arrangement of the CMOS image sensor will be described with reference to FIG. 5.
As the photoelectric converter 301, a photodiode 401 is used. The photodiode 401 is made up of a p-type well formed in a silicon substrate, and an n-type impurity region formed from the surface of the silicon substrate in the well. When light is incident on the photodiode 401, electron-hole pairs are produced in the n-type impurity region. In the n-type impurity region, holes move to the p-type well, and only electrons are left. That is, charges are accumulated in the n-type impurity region of the photodiode 401 by irradiation of light. The accumulated charge amount changes depending on the intensity of incident light, and serves as signal charges.
A 1-pixel video signal by signal charges is amplified by a transistor 402 which receives a power supply voltage VDD via a power supply line 411. The transistor 402 is connected to the power supply line 411 via a contact 411a. The contact 411a corresponds to the contact 303a in FIG. 4.
The 1-pixel video signal is output from a signal output terminal 431 by selecting a transistor 403 by a signal from a vertical scanning shift register 421 and selecting a transistor 404 by a signal from a horizontal scanning shift register 422. When a reset signal is input to a transistor 405, the power supply voltage VDD is input to the photodiode 401 to erase the remaining charges.
The transistors 402, 403, and 405 in FIG. 5 are formed in the circuit region 302 in FIG. 4. When light is incident on the circuit region 302, the transistors 402, 403, and 405 malfunction. To prevent this, the light-shielding member 310 (FIG. 4) covers the circuit region 302.
Video signals for respective pixels output from the photodiodes 401 arranged in a matrix and amplified by the transistors 402 are sequentially extracted as image signals by the vertical and horizontal scanning shift registers 421 and 422.
The photoelectric converter 301 and opening 311 shown in FIG. 4 cannot be excessively downsized in terms of reception of light. For example, the opening 311 cannot be excessively downsized in consideration of the wavelength of light to be received. For this reason, the characteristics of the CMOS image sensor degrade if the integration degree is increased by downsizing the photodiode of the photoelectric converter 301 and the opening 311.
As shown in FIGS. 4 and 5, the power supply line for supplying the power supply voltage VDD need not be prepared for each of adjacent photoelectric conversion cells 305. That is, as shown in FIG. 6, one power supply line 411 is commonly used for photoelectric conversion cells 305 adjacent in the X direction, which can substantially halve the number of power supply lines 411. As a result, as shown in FIG. 7, the power supply line suffices to be arranged every other Y-direction wiring region 303, and the integration degree can increase. In this case, as shown in FIG. 6, circuit regions 302 adjacent in the X direction are connected to the power supply line 411 via a common contact 411b. 
However, if the integration degree is increased by the above method, the pitches between the openings 311 of the photoelectric converters 301 in the X direction become different, and a reproduced image partially shifts from the optical position of an object.
More specifically, as shown in FIG. 7, a distance d1 between openings 311 adjacent in the X direction via the Y-direction wiring region 303 is different from a distance d2 between openings 311 directly adjacent without the mediacy of the Y-direction wiring region 303. However, pixels are arranged at an equal pitch in image reproduction, so an accurate image cannot be reproduced.
It is an object of the present invention to provide a solid-state image sensing device capable of obtaining a more accurate image reproduction state with a higher integration degree.
To achieve the above object, according to the present invention, there is provided a solid-state image sensing device comprising a plurality of photoelectric conversion cells which have photoelectric converters for photoelectrically converting optical signals and are arranged in a matrix to accumulate the photoelectrically converted signal charges, the photoelectric converters being adjacent to each other at different pitches in a predetermined direction, a light-shielding member which covers the photoelectric conversion cells arranged in a matrix, and a plurality of openings which are formed in the light-shielding member in correspondence with the photoelectric converters, and pass optical signals to the photoelectric converters, the openings being arranged at an equal interval in a predetermined direction.